In EP-0,387,771 there are described benzopyran derivatives which show an inhibitory activity on Maillard reaction and possess an antioxidizing effect. In Arzneim.-Forsch. 25 (9), p. 1404 (1975) there is described [2-[(2,3-dihydro-1,4-benzodioxin-2-yl)methyl]-amino]ethylguanidine in a study concerning noradrenaline depletion effects. In WO-83/03607 a number of cyanoguanidines are described having anti-hypertensive and vasodilator activity. Our novel compounds differ in that they have selective vasoconstrictor activity.